JP3198314B2 - Wet disc brake - Google Patents

Abstract

PCT No. PCT/AU92/00540 Sec. 371 Date Apr. 11, 1994 Sec. 102(e) Date Apr. 11, 1994 PCT Filed Oct. 9, 1992 PCT Pub. No. WO93/07402 PCT Pub. Date Apr. 15, 1993The present invention relates to a brake assembly and a pad configuration for use therein which is capable of use in corrosive environments without significant damage occurring to the assembly from such usage. The assembly comprises a single disc, a housing surrounding the disc which together with rotary seals provides a substantially sealed zone within which an annular braking surface of the disc rotates, and at least one friction pad having a friction surface adapted to be moved against the braking surface to provide a braking effect. The friction surface has a leading edge which is swept or angled rearwardly from a radial line passing through an inner leading edge corner of the friction surface and one or more grooves which are open at both ends and which are also angled rearwardly from a radial line passing through an inner forward end of each groove.

Description

Description: FIELD OF THE INVENTION The present invention relates to improvements in disk assemblies and components therefor, and more particularly, but not exclusively, to small work vehicles (light utility motor vehicles). About what is being done.

Conventional small work vehicles are now readily implemented for mining premises and around them for the role of employee transportation. In such locations, the brake housing and its components are subject to splashing or immersion in highly corrosive liquids. Besides,
In some situations, such as when driving in or around the sea or salt water, the vehicle wheels and brake assembly are prone to contact with corrosive liquids. In these and other similar uses, many components do not have reasonable low maintenance or reliability when used on public roads. This is due to the severity of the conditions encountered in the mine premises and on the commercial road leading to the mine or other uses as described above.

Exposed perimeter dry friction brakes used in light duty vehicles on the market are significantly affected by operating conditions. Wear dust scattered on the road,
Also, due to frequent flooding of water and mud on the work site,
High part wear rates and high part corrosion rates are caused. In these locations, dissolved salts and dissolved minerals are present in the groundwater and the wear of the brakes due to corrosion can be very severe and cause unacceptable safety hazards.

As trackless vehicles have become more common in the mining field, multiplate oil immersion friction brakes have become widely used. This is to isolate the vehicle braking system from surrounding harmful substances. The disadvantage of multiplate brakes is that they require completely different mounting positions than conventional dry friction brakes, and that different actuation systems are applied. Thus, the multi-plate type closed brake system is suitable only for a custom designed mechanism.Mechanisms such as the wheel disc shape, the arrangement of the wheel fasteners, the hub dimensions and the brake operation system meet the requirements of the multi-plate brake. It can be chosen at the design stage to meet. Multiplate brakes also have the disadvantage that only one braking action system can be used per wheel, without major modifications. In other words, if independent or separate pads, more than one pair of pads can be used per wheel, and at least one pair of pads can be actuated by an independent actuation system to act as a side brake. it can. In addition, multi-disc brake assemblies require that composite (i.e., friction material) discs with softer surfaces rotate to facilitate cooling. This is because oil is difficult to circulate as a result of bundling and stacking disks without gaps. Thus, the oil also needs to operate the pump to flow over or through the metal parts. This problem does not occur with a single disk / separation pad configuration. This is because the use of thicker metal disks and the natural and uniform heat transfer by rotating the disks results in a much more advantageous heat sink system. As a result, even when designed as an original accessory, multi-disc brakes tend to be more complex and expensive than a single metal disc brake having opposing friction pad pairs.

Introduced non-market vehicles equipped with a single disc (or drum) dry friction brake system exposed to the environment to reduce employee transportation costs in and around the mine I have been. The key to using these low-cost vehicles is that after an appropriate driving cycle, to recover some of the capital expenditure,
Is it possible to resell?

In such vehicles, any retrofitting of the brake system must not significantly change the vehicle. Otherwise, first of all, there is no reason to use regular vehicles on the market. In essence, no matter where the brake mounting position and the wheel fixing fastener arrangement are available in a unitarily produced vehicle on the market,
The braking system applied to it must be maintained to meet the requirements of the market.

As a result of the above, the design elements of the modifiable product are clearly set. A brake system suitable for conversion to a small work vehicle on the market should preferably meet the following requirements, or at least approach these requirements: 1. Can be reversed at a later date That require only the slightest axle change.

2. Fits the brake position provided by the original manufacturer and is bolted to its current configuration.

3. Utilize higher performance clone type friction.

4. As far as possible, a braking characteristic equivalent to that provided by the OEM brake when it is brand new must be obtained.

The original equipment market (OEM) also demands environmentally friendly braking systems. The system is
It minimizes or prevents the emission of friction material dust into the atmosphere due to wear of the pad material during use. Of course, this applies both to brake systems that must be provided in vehicles used in dirty environments and to brake systems provided in mere road vehicles that do not normally suffer from dirty use environments. Of course, such a brake system should not be too expensive compared to conventional existing dry brake systems, and in fact is significantly more than existing wet or oil-immersed systems such as the multi-disc system described above. It is desired that the cost should be reduced. A major reason for the low cost of dry friction brakes is that wet disc brakes use viscous shear, whereas they use clone friction. With this viscous shearing force, only about 1/5 torque per unit area is obtained. In order to make oil-immersed multi-disc brakes commercially applicable, a mounting arrangement substantially different from conventional dry friction brakes is required.
And, in fact, they are more complex and expensive. These mean the following: That is, the structure of the conventional multi-plate oil-immersed wet disc marketed today is not suitable for use as a small working vehicle that is usually on the market after use, and it is cheaper than others. When there is a system that is simpler and of comparable performance, it is undesirable to use the wet disc as an original accessory in such vehicles.

Accordingly, it is an object of the present invention to provide a brake system suitable for general vehicles and special vehicles such as those described above, the brakes of which are similar to standard dry brake devices commonly distributed in vehicles at the time of manufacture. Nevertheless, it can operate in a harsh or contaminated environment with sufficient life and operating characteristics. Further, preferably, the wear of the friction material is reduced,
It is another object of the present invention to provide a brake system that minimizes the emission of friction material dust into the atmosphere while maintaining a simple structure and effective operation. It is still further preferred to provide an improved brake pad configuration, preferably adapted to improve braking performance in a liquid medium, and more preferably, even in a liquid medium, By utilizing the working properties,
An object of the present invention is to provide a configuration of a brake pad designed to improve braking performance.

Accordingly, the present invention provides a disk brake assembly for a vehicle adapted to couple to an axle end, the assembly comprising a single rotor disk adapted to rotate with the axle end, one or two disks. A fixed housing surrounding the rotor with one or more seals, the seals operative to form a substantially sealed area surrounding at least the braking portion of the rotor disk, the assembly comprising: Further, in the brake application section, there is at least one friction pad disposed proximate to a brake surface of the rotor disk, wherein the one or each friction pad is pivoted toward the brake surface of the rotor disk. Direction to engage this surface, or to move axially away from the rotor. Liquid filling means arranged to disengage from braking on the disk, said assembly further provided to allow at least a portion of the area surrounding the rotor disk to be filled with a liquid medium It consists of Advantageously, the disc brake assembly is in use filled with liquid to at least a level above the or each rotary seal. Advantageously, said assembly has at least one pair of said friction pads, at least one of said pair of friction pads being positively movable towards said rotor disk when a brake is applied. is there. Thus, the use of a single rotor disk with one or more pairs of friction pads makes the brake system compatible with the original accessory dry disk vehicle brake assembly. Can be. The liquid filling means allows the closed area to be filled with liquid to a certain extent. The limit is a limit that effectively prevents the entry of dust and corrosive liquids through the rotary seal. This is because the rotary seal is the main entry point for all such contaminants. The liquid medium also minimizes the generation of dust particles on the friction material, and the rotary seal prevents or minimizes any such particles from leaking into the atmosphere. The liquid also has a cooling effect on the brake components.
However, it will be readily appreciated that the liquid medium can have a detrimental effect on the friction or braking characteristics of the assembly as a result of the liquid medium. This is because the liquid medium causes separation of the brake friction pairs and also fills irregularities on the rotor surface with a medium that is virtually incompressible.

Several configurations or means may be applied individually or in any combination to improve the friction or braking characteristics of the assembly. One such arrangement is to provide at least one pair of friction pads not at a position below a horizontal line passing through the axis of rotation of the rotor disk. Preferably, at least one pair of friction pads may be provided, at least in part, located in the front and upper quadrant of the rotor disk. However, the front refers to the normal forward direction of the vehicle. These arrangements, although not critical, assist in braking performance. Even if it works well in other physical locations. Of course, additional logarithms of the pad could be used if desired. In a particularly preferred embodiment, the front edge of the pad is swept back, i.e., inclined, from the radially inner front angle of the pad to the rear with respect to the direction of rotation of the rotor disk. That is, the pad has a receding angle rearward from a radial line passing through a radially inner front angle of the pad, that is, the pad is inclined. Advantageously, an actuating means is provided for each of said friction pads, whereby the pads move positively towards the brake surface of the rotor disk during braking. In addition, it is advantageous if the actuating means is such that the pressure applied to the front edge of the friction pad during braking is greater with respect to the pressure applied to the rest of the friction pad. This will improve the removal of liquid (ie, oil) from the pad area. That is, the removal is made by the pad leading edge firmly pressed against the rotor disk, particularly where the leading edge of the pad is swept backwards or inclined as described above. Said actuating means is at least two actuating pistons acting on the friction pad, one of said pistons acting at least in close proximity or partially over the front edge of the friction pad, and One piston (or a plurality of pistons) is arranged rearwardly therefrom. In an even more preferred embodiment, the grooves are provided in the friction surface of the friction pad and extend to a depth corresponding to an acceptable safe operating level of the friction material. It is so deep that the groove remains beyond the full operating life of the pad. Preferably, each groove has a rectangular cross section and is provided to be inclined rearward. At this time, the pad is provided with a receding angle, that is, parallel to the inclined front edge, or inclined at an acute angle with respect to the front edge of the pad. Preferably, each groove is continuous, that is, without any breaks in a straight line or curve, and extends from the radial inner circumference of the pad to the radial outer circumference of the pad or to the rear edge of the pad. Preferably, the grooves are about 2 mm wide and about 5 mm deep. However, effects can be obtained with grooves having other dimensions, although the efficiency is not necessarily good.

Advantageously, the trailing edge of each groove (with respect to the leading edge of the pad) is perpendicular to the friction material surface or inclined rearward from its normal. The angle of inclination from the perpendicular is preferably 0
゜ 30 °, more preferably about 15 °. Advantageously, the density or number of grooves is relatively higher near the leading edge of the pad, as compared to the number of grooves near the trailing edge of the pad.

Furthermore, the present invention also provides a structure of the brake pad. Thus, the front edge of the pad is swept back, or inclined, rearward from a radial line passing through the inside front angle of the pad.

Still further, the present invention provides a brake pad having the following structure. It has a front edge, a rear edge, an inner peripheral edge, and an outer peripheral edge, surrounded by a friction surface, wherein the brake pad structure has at least one groove extending inward from the friction surface. Wherein the one or each groove extends between the front edge or the inner peripheral edge and the outer peripheral edge or the rear edge, and the one or each groove at the front edge or the inner peripheral edge Extend rearward in use at an acute angle with the radial line.

Advantageously, the or each groove extends in a substantially continuous straight line or curve. Advantageously, the leading edge of the pad is swept back, i.e. inclined, from a radial line passing through the inner forward corner of the pad. Preferably,
The trailing edge of each groove is perpendicular to the brake surface of the pad,
Or, it is better to incline backward (with respect to the front edge) at an angle of 0 to 30 °. Advantageously, the density or number of grooves in the region near the front edge is greater than the density or number of grooves in the region near the rear edge of the pad. The groove configuration described above facilitates the removal of liquid from the brake surface of the rotor so that the brake surface engages the pad when the brake is applied.

Hereinafter, for some preferred embodiments of the present invention,
This will be described with reference to the accompanying drawings. 1 and 2 are front views showing the structure of two preferred brakes according to the present invention; FIG. 3 is a cross-sectional view of a main part taken along the line AA of FIG. 1; FIG. 5 is a cross-sectional view of a main part of plane BB of FIG. 1; FIG. 5 is a cross-sectional view of a main part of plane CC of FIG. 1; 7 to 10 are schematic diagrams showing various friction pad shapes according to a preferred embodiment of the present invention, and FIGS. 11A and 11B show two types of friction pads along lines XI-XI in FIGS. It is a principal part sectional view which shows the shape of the applicable groove | channel.

As shown in FIGS. 1 and 3, the brake assembly in this preferred embodiment has a rotor disk 3 secured to the axle end A by bolts. The radially outer circumferential portion of the disc 3 has an annular braking surface 40 on the opposite side to which one or more independent brake pads 10 are engageably provided. I have.
An actuator 4 is arranged on each pad, such that each pad is positively moved with respect to one of the corresponding braking surfaces 40. The actuator may have a pair of piston members 14 that are configured to be moved by hydraulic pressure acting on the outwardly facing surfaces of the piston members through passages 17. The seals 5, 6 may be provided on the wall of the cylinder space where the piston member 14 moves (FIG. 4). The actuator in this embodiment has a pair of piston members 14 circumferentially spaced along a pad 10, as best shown in FIG. As shown in FIG. 1, the radial center line 42 of the pad actuator 4 may be located in the upper half of the rotor disk 3, and more preferably, at least one pair of pads is located on the front and upper four It is better to be located within the dividing circle 43.
The housing, which is divided into two parts 1,2, is provided surrounding the hub and the disc 3, providing a substantially closed shield area 44, which area is provided with rotary seals 18,19,20. Sealed by. The liquid level is
41, where the rotary seals 18, 19, 20 always hold the liquid inside, prevent contaminants from penetrating therethrough, and remove dust therefrom. It keeps out pollutants.

FIGS. 2 and 6 illustrate a second preferred embodiment, in which the same reference numbers are assigned to configurations similar to those of FIGS. 1 and 3-5. In this example,
Two pairs of friction pads are provided such that each pair is located directly opposite the assembly. In this embodiment, only a pair of friction pads may be operably used if sufficient braking characteristics are obtained.

In this embodiment, the hub and the disc 3 are in two parts, the first inner part, the hub 60, being adapted to be bolted or otherwise fixed to the wheel end, and to the second part. The outer portion (disk) 61 is connected to the inner portion 60 by a spline connection portion 62. The outer portion 61 of the rotor disk has mutually opposite annular braking surfaces 40 adapted to be engaged by the friction pads 10. The spline connection allows the outer part 61 of the rotor disk, which is subject to wear, to be easily removed for repair or replacement. Other coupling structures between the inner and outer portions can be used if desired. However, in the case of the spline connection part 62,
The further advantage is that the outer part 61 can be moved in the axial direction, so that only one positively active device 4
Only each pair of pads 10 is enabled. However, it is preferable to use two such actuators 4, each of which preferably has a pair of piston members 14.

The assembly also has a pair of housing members 1, 2 defining a region 44 in which the outer rotor portion 61 rotates. This area 44 is provided with a rotary seal 6 acting between the rotating inner part 60 of the rotor and the stationary housing members 1, 2.
Sealed by 3.64. Piston member for each actuator
14 is disposed on one of the housing members 1 or 2. Typically, hydraulically operated brake assemblies (eg, dry friction brakes) require some positive return device to move the piston member a sufficient distance from the rotor disk when braking is not required. This is done via a suitable return spring or hydraulic means. Alternatively, it is provided by a horned annular sealing ring which is arranged on the wall of the piston cylinder and has the desired return effect when the hydraulic pressure causing the braking from the piston is released. However, in the present invention, it is not necessary to move the piston member a sufficient distance from the rotor disk when the braking effect is not required, since the brake pad is operating effectively in the liquid oil bath. As shown in FIG. 6, the seal ring 65 of the piston may be provided on the piston member 14 rather than on the cylinder wall, and with this arrangement hydraulic pressure is removed from the spaces 66, 67 as a result of the braking effect being no longer required. When removed, piston member 14 can be moved sufficiently far from the rotor disk. Of course, appropriate hydraulic fluid couplings (not shown) may be provided in the spaces 66 and 67 to supply the pressure fluid for activating the brake or to remove the pressure fluid therefrom when the braking effect is not required. Will be.

In the embodiment shown in FIGS. 2 and 6, provision is also made for the area 44 to be completely or partially filled with liquid oil, for example via a port closed with a plug 23.

7 to 10 illustrate some preferred shapes of the pad structure made of the desired friction material. In each figure, the dotted line represents the rotor 3 and the arrow 45 represents the direction of rotation of the rotor 3 passing through the pad 10. Pads are front 46, rear 4
7. It has an inner peripheral edge 48 and an outer peripheral edge 49. The front edge 46 is a series of curves or straight lines with a rearward receding angle.
It passes through the inner forward corner of the pad and has a radial line
It forms an acute angle x with 50. As shown in FIGS. 8 and 9, the front edge of the friction material 55 may be inclined backward as described above, in contrast to the back plate 70. Preferably, the front inclined edge 71 of the friction material extends from the front inner corner 51 as shown. Further, the rear inner corner of the friction material may be removed along the slope line 72 as shown. Preferably, the back plate
Front edge 46 of 70 may be received and secured in notch 73 with pad fastener 74, thereby preventing incorrect mounting of the pad. In this configuration, if desired, the grooves can be
And it can be curved as shown in FIG. The various configurations of the front edge of the rearwardly sloping friction material disclosed herein guide the oil film outward from the rotor surface and away from the pad, thereby affecting the effect of the oil film on the friction characteristics. An effect is provided that acts to minimize. If desired, a wiper member may be added in front of the front edge to further limit the effect of the oil film on frictional properties. The effect is that the actuator 4
Improvements may be made by ensuring that more pressure is applied to the front edge 46 as compared to the rear edge 47. dotted line
68, 79 schematically represent the position of the working piston 14. As shown there, the position 68 of the front piston 14
Partially protrude from the front edge 46 in order to relatively increase the pressure applied to the front edge 46. In addition, this effect may be improved by tilting the front edge rearward from the normal of the rotor disk brake surface 40 by an angle of 0 ° to 30 °. It is preferable that the pair of grooves 52 and 53 extend from the pad edge 48 to either the pad edge 49 or 47 as shown. This also
Also, the liquid oil can be directed outward through the groove and away from the friction surface 55 of the pad. The grooves may be provided in a straight line as shown at 52, or may be provided in a curved line as shown as 53, both preferably forming an acute angle with the radial line 56 at the inner peripheral edge 48. It is better to form it. These acute angles are desirably equal to or larger than the angle x, and the angles are desirably provided so as to increase in the direction from the front edge 46 to the rear edge 47. As shown in FIGS. 9 and 10, the number of grooves per unit area in the front area of the pad is preferably greater than that in the rear area of the pad. This may also improve the removal of liquid oil from the brake surface. As shown in FIGS.11A and 11B, the cross-sectional shape of the grooves 52, 53 may be provided in a rectangular shape, but preferably the trailing edge of each groove is perpendicular to the brake surface. Alternatively, it is better to incline backward as shown in FIG. 11A. The angle to this perpendicular is from 0 ° to 30
よ く is good, preferably about 15 °. The depth of the groove should be deep enough so that it can still work beyond the full service life of the pad. The trailing edge of one or each groove should be a substantially sharp edge, that is, an edge that is not radial or chamfered.

Continuation of the front page (56) References JP-A-61-24842 (JP, A) JP-A-58-77935 (JP, A) JP-A-54-44376 (JP, U) JP-A-62-176533 (JP, A) 62-126623 (JP, U) JP-A-2-93537 (JP, U) JP-A-3-2930 (JP, U) JP-A 56-62426 (JP, U) JP 60-108839 (JP, U) Japanese Utility Model 52-82685 (JP, U) Japanese Utility Model 56-157438 (JP, U) Japanese Utility Model Application 50-106581 (JP, U) Australian Patent 212523 (AU, A) Australia Patent 209148 (AU, A) Australian Patent 153857 (AU, A) British Patent Application Publication 2115507 (GB, A) British Patent 1124004 (GB, B) International Publication 82/3255 (WO, A1) West German Patent Application Publication 2539557 ( DE, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16D 55/22 F16D 69/00

Claims (12)

(57) [Claims] 1. A disk brake assembly for a vehicle adapted to be coupled to an axle end, the disk brake assembly being adapted to rotate with the axle end, a single rotor disk;
A fixed housing surrounding the rotor disk with one or more seals, the seals operative to form a substantially sealed area surrounding at least the braking portion of the rotor disk; The disc brake assembly also includes oil filling means provided to allow at least a portion of the substantially enclosed area to be filled with oil, whereby the brake working portion of the rotor disc is provided. The disc brake assembly further includes at least one friction pad disposed proximate to a brake application portion of the rotor disk, the at least one friction pad being adapted to pass through the oil. Move in the axial direction toward the brake application portion of the rotor disk and engage to apply a brake. Wherein the at least one friction pad comprises a friction surface having a front edge, a rear edge, an inner peripheral edge, and an outer peripheral edge and surrounded by the at least one friction pad; A friction surface having at least one groove, one or each groove extending between the front edge or the inner peripheral edge and the outer peripheral edge or the rear edge, wherein the one or each groove is a longitudinal axis of the groove; Make an acute angle with the radial line at each point in the direction,
A disk brake assembly extending rearward and outward in use. 2. The disc brake assembly according to claim 1, wherein the trailing edge of said or each groove forms an angle of between 60 ° and 90 ° with said friction surface. 3. The disc brake assembly according to claim 1, wherein the or each groove is an arc-shaped curve continuously inclined rearward. 4. An arrangement interval of the grooves in a first region near a front edge of the friction pad is smaller than an arrangement interval of the grooves in a second region near a rear edge of the friction pad. The disc brake assembly according to any one of claims 1 to 3, wherein: 5. The friction pad of claim 1 wherein said front edge is recessed rearwardly from a radial line passing through an inner front corner of said pad.
5. The disc brake assembly according to claim 4. 6. The disc brake assembly according to claim 1, wherein the one or each groove has a width of 2 mm and a depth of 5 mm. 7. The method of claim 1, wherein said one or each groove has a depth sufficient to effectively survive the operation of the friction pad beyond its operating life. Any one
Disc brake assembly according to any one of the preceding claims. 8. A method according to claim 1, wherein at least one pair of said friction pads is provided, and at least one of said pair of friction pads is provided.
The disc brake assembly according to claim 1, wherein the individual is capable of positively moving toward the rotor disc when a brake is applied. 9. The disc brake assembly according to claim 8, comprising at least two pairs of said friction pads. 10. The friction pad of at least one of the pair is positively moveable toward the rotor disk by at least two actuators, one of the actuators being the at least one of the at least one friction pad. 10. The disc brake assembly according to claim 8, wherein the friction pads are arranged so as to apply an actuation force directly toward the front edge of the friction pad in a direction toward the rotor disc. 11. The friction pad according to claim 8, wherein said at least one pair of said friction pads is disposed at a position substantially not lower than a horizontal line passing through a rotation axis of said rotor disk.
11. The disc brake assembly according to any one of claims 10 to 10. 12. A brake pad structure for use in a brake assembly and adapted to provide a braking action to a rotatable disc, the brake pad structure comprising a front edge, a rear edge, and an inner edge. A friction surface defined by and having a peripheral edge and an outer peripheral edge, wherein the brake pad structure is characterized by at least one groove extending inward from the friction surface; Is extended between the front edge or the inner peripheral edge and the outer peripheral edge or the rear edge, and the or each groove forms an acute angle with a radial line at the front edge or the inner peripheral edge, A structure of a brake pad extending rearward in use, comprising: a plurality of grooves; a first pad adjacent to a front edge of the pad structure;
The structure of a brake pad, wherein the density of the grooves in the area is greater than the density of the grooves in the second area near the rear edge of the pad.